dpmd_programs.c

Linux下动态电源管理(Dynamic Power Management)的用户守护进程

#include <ctype.h>
#include <dirent.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define PRG_LENGTH 64

struct prog_list {
	char name[PRG_LENGTH];
	struct prog_list *next;
};

static struct prog_list *running_programs = 0L;

/* int numeric_entry(const struct dirent *d) 
 *
 * Select function for scandir()
 *
 */
static int numeric_entry(const struct dirent *d) {
	return isdigit(d->d_name[0]);
}

static int free_programs(void)
{
	struct prog_list *prog = running_programs;

	while (prog) {
		free(prog);
		prog = prog->next;
	}

	running_programs = 0L;

	return 0;
}

static int insert_programs(char *progname)
{
	struct prog_list *prev, *prog;

	prev = prog = running_programs;

	while (prog) {
		prev = prog;
		prog = prog->next;
	}

	prog = (struct prog_list *)malloc(sizeof(*prog));
	if (!prog) {
		return -1;
	}
	memset(prog, 0, sizeof(*prog));

	memcpy(prog->name, progname, PRG_LENGTH);

	if (prev)
		prev->next = prog;
	else
		running_programs = prog;

	return 0;
}

int find_program(const char *progname)
{
	struct prog_list *prog = running_programs;

	while (prog) {
		if (!strcmp(prog->name, progname))
			return 1;

		prog = prog->next;
	}
	return 0;
}

int print_programs(void)
{
	int i = 0;
	struct prog_list *prog = running_programs;
	
	while (prog) {
		printf("%d: %s\n", i++, prog->name);
		prog = prog->next;
	}
	return 0;
}

/* int get_running_programs(void)
 *
 * looks for running programs and fills the 
 * global struct running_programs.
 *
 * Returns the length of the newly created list.
 */
int get_running_programs(void)
{
	struct dirent **namelist;
	int n=0, ret=0, n_chars=0;
	char file[PRG_LENGTH];
	char program[PRG_LENGTH];
	char *prg_basename;

	free_programs();

	n = scandir("/proc", &namelist, numeric_entry, NULL);

	if (n < 0) {
		printf("scandir: %s\n", strerror(errno));

	} else {

		while(n--) {
			snprintf(file, PRG_LENGTH - 1, "/proc/%s/exe", namelist[n]->d_name);    
			free(namelist[n]);

			n_chars = readlink(file, program, PRG_LENGTH - 1);

			if (n_chars < 0) {
				/* probably this process is a kernel process or 
				 * user cannot read the link or
				 * has disappeared while scanning, don't worry */
#if 0
				printf("%s: %s\n", file, strerror(errno));
#endif
				continue;
			}
			/* terminate the string */
			program[n_chars] = '\0';
			prg_basename = rindex(program, '/');
			prg_basename++;
			if (prg_basename == NULL)
				prg_basename = program;
			insert_programs(prg_basename);

			ret++;
		}
	}
	free(namelist);
	return ret;

}